Although the optimization problem (REF ) is clear in its form, it can not be directly solved since it involves infinite-dimensional variable optimization due to the continuity of the dictionary \(\mathcal {A}\) .
To cope with this issue, a conventional approach is to discretize the angle domain into a grid, which forms a discrete Fourier transform (DFT) dictionary [1]}.
This approach, however, induces the off-grid error since the AOAs will not lie exactly on the grid, which may significantly degrades the recovery performance [2]}.
In the following, we develop an efficient algorithm for solving the optimization problem (REF ).
